In vitro activity of the novel ketolide HMR 3647 and comparative oral antibiotics against Canadian respiratory tract isolates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis

The in vitro activities of HMR 3647, erythromycin A, clarithromycin, azithr omycin, roxithromycin, penicillin G, ampicillin, cefuroxime, trimethoprim/s ulfamethoxazole, tetracycline, ciprofloxacin, and levofloxacin were determi ned for 1179 Streptococcus pneumoniae, 1438 Haemophilus influenzae, and 428 Moraxella catarrhalis isolated from respiratory tract specimens by 18 medi cal centers across Canada during 1997-1998. On a per weight basis, HMR 3647 was the most active agent tested against S, pneumoniae with MIC(90)s of le ss than or equal to 0.12 mu g/mL for both penicillin susceptible and penici llin intermediate isolates and 0.25 mu g/mL for penicillin-resistant isolat es. HMR 3647 was also highly active against M. catarrhalis (MIC90, less tha n or equal to 0.12 mu g/mL), but less active against H. influenzae (MIC90, 4 mu g/mL). (C) 1999 Elsevier Science Inc.